1. Field of the Invention
The present invention relates to a support plate, for a solid-state imaging element, for supporting a circuit board on which a solid-state imaging element is mounted, a method for manufacturing a support plate, and a solid-state imaging device.
2. Description Related to the Prior Art
A solid-state imaging device comprises a taking lens, a solid-state imaging element disposed behind the taking lens, a circuit board on which the solid-state imaging element is mounted, and a support plate, for the solid-state imaging element, that supports the circuit board. The solid-state imaging device is incorporated in an electronic device such as a digital camera, a mobile phone with a camera, a smartphone, or the like. The solid-state imaging element is an image sensor of a CCD-type, a CMOS type, or the like. The solid-state imaging element photoelectrically converts light incident on a light receiving surface to output three color signals. The three color signals are subjected to signal processing in a signal processing circuit incorporated in the electronic device, and then converted into image data. A taken image is displayed on a monitor based on the image data.
The sensitivity of the solid-state imaging element to the near-infrared region is higher than that of a human eye. In the case where the whole light including the IR (infrared light) is incident on the solid-state imaging element and photoelectrically converted, an image of a subject seen with human eyes and a taken image differ in color balance. For example, a green object appears as a gray or a reddish brown object and a blue-violet object appears as a red-violet object in the taken image.
In a solid-state imaging device described in U.S. Patent Application Publication No. 2012/0257075 (corresponding to Japanese Patent Unexamined Application Publication No. 2012-222546), an IR cut filter, which cuts the infrared light while transmitting visible light, is provided between a taking lens and a solid-state imaging element to prevent the infrared light from entering the solid-state imaging element. Thereby, the color balance seen with the human eyes is reproduced in a taken image. In the solid-state imaging device described in the U.S. Patent Application Publication No. 2012/0257075, the IR cut filter is held by a frame-shaped frame member (which corresponds to a support plate for a solid-state imaging element of the present invention), and the frame member holds a circuit board on which the solid-state imaging element is mounted.
In the solid-state imaging device described in the U.S. Patent Application Publication No. 2012/0257075, the IR cut filter cuts the infrared light, but the visible light from the taking lens passes through the IR cut filter. After passing through the IR cut filter, the visible light is incident on the solid-state imaging element, but some of the visible light travels toward an inner wall of the frame member. The light directed to the inner wall of the frame member is reflected by the inner wall of the frame member and acts as harmful rays. Upon incidence on the solid-state imaging element, the harmful rays may cause so-called flare that is light fogging, resulting in degradation of image quality. Furthermore, the harmful rays may cause a phenomenon called “ghost” which is a clear appearance of the harmful rays in an image.